The children’s title “And Tango Makes Three” sparked controversy when it was first published in the United States in 2005. The illustrated book tells the real-life story of two male penguins who hatched an egg together at New York’s Central Park Zoo.

For six years “And Tango Makes Three” was one of the most challenged books in U.S. public libraries. But attitudes about same-sex couples have changed a lot in the U.S. in recent years. After several years at or near the top the American Library Assn.’s list of the most challenged books, “And Tango Makes Three” didn’t even make the top 10 in 2013.

But in Singapore, however, library officials have decided they can’t stomach gay penguins--not in a society where sex between men is still punishable by jail time. Last week, they ordered “And Tango Makes Three” and two other children's books that take up themes of same-sex parenting removed from libraries there.

The books are to be destroyed, or “pulped.” The other titles are “The White Swan Express,” which tells the story of children adopted by straight, gay, mixed-race and single parents; and “Who's In My Family,” an illustrated book that includes gay couples in its portraits of family diversity.

The decision by Singapore’s National Library Board has sparked outrage in the nation’s literary community. On Wednesday, three writers resigned their posts as jurors in the Singapore Literature Prize in protest.

The writers T. Sasitharan, Romen Bose and Robin Hemley said in a statement that the decision was “bigoted and sets a very worrying precedent that it is acceptable to discriminate against anyone who may hold differing values and opinions.”

And on Thursday, one of the city-state’s most prominent writers, novelist Suchen Christine Lim, added her voice to the growing clamor about the library’s decision. Lim told an audience at the Asia Pacific Writers and Translators Assn. conference in Singapore that she, too, had been raised in an unconventional family--as the daughter of a single parent.

"In removing and pulping those books on various family structures, the National Library Board is telling these children that they and their families don't count,” Lim said. “In removing these books, NLB is reducing such children and their families into invisibility."

The Singapore library officials said they were acting in defense of a "pro-family" policy. Several Singapore writers have labeled the destruction of the titles "book burning" and are calling for a boycott of library events.